Encyclopedia Astronautica
EMPIRE General Dynamics

General Dynamics Empire concept
Credit: © Mark Wade
Empire Comparison
Comparison of Empire designs, from left to right:
Credit: © Mark Wade
American manned Mars flyby. Study 1962. General Dynamics' manned Mars orbiter spacecraft design of 1962 had a total mass of 900 metric tons and would be launched into low earth orbit with a two launches of a Nova booster or eight launches of a Saturn V.

The 15-month mission would be launched toward Mars in March 1975.

EMPIRE was the first series of Mars mission studies conducted under NASA's auspices. The goal of the studies was to identify mission alternatives and estimate spacecraft masses for initial manned Mars flyby and orbiter missions. The primary objective was to identify payload requirements for Nova, the series of super heavy lift launch vehicles planned after the Saturn series. A secondary objective was to identify stage and engine requirements for NERVA, the AEC/NASA nuclear thermal engine program. The Marshall Space Flight Center's Future Projects Office, led by Heinz Koelle, let contracts for the studies to industry in May 1962. Three contractors were selected: Aeronutronic, General Dynamics, and Lockheed.

Krafft Ehricke led General Dynamic's EMPIRE team, and the result was an exhaustive study of Mars orbiter and even landing missions. GD proposed assembling the spacecraft in low earth orbit using multiple Saturn V or Nova launches. A crew of 8 would be sent on a 15-month Mars orbiter mission departing in March 1975. The crew would occupy the primary crew ship, but be accompanied by two service spacecraft. The service craft would provide a source of spares in the event of damage to the primary spacecraft during the voyage.

Four spacecraft configurations were considered in the final report:

  • C-22, 106 m long, assembled from Nova-launched components with a 21 m diameter, and using near-term RIFT (55 metric ton thrust) or later NERVA (182 metric ton thrust) nuclear thermal engines. The spacecraft would be assembled in two launchings of 450 metric ton payload Nova boosters.
  • C-23, 95 m long, assembled from Nova-launched components with a 23 m diameter, and using advanced nuclear thermal engines. The spacecraft would be assembled in eight launchings of 120 metric ton payload Saturn V boosters.
  • C-26, 162 m long, assembled from Saturn V-launched components with a 10 m diameter, and using near-term RIFT (55 metric ton thrust) or NERVA (182 metric ton thrust) nuclear thermal engines.
  • C-28, 174 m long, assembled from Saturn V-launched components with a 10 m diameter, and using advanced nuclear thermal engines.

The re-entry vehicle (the EEM 'Earth Entry Module) was an enlarged Apollo command module, able to accommodate the crew of eight. A standard 10 m diameter command module, with a three-man control deck and five-man sleeping deck, would be common in all configurations. This would also serve as a radiation shelter during solar flares. Mission modules of the same diameter would be clustered around the command module, tailored to specific missions.

A 3-m diameter, 23-m long spindle separated the crew spaces from the SNAP-8 nuclear power generator. During periods of coasting, the spacecraft would be spun up to provide the crew with 0.25 G of artificial gravity.

A number of robot probes would conduct research while the spacecraft was in Martian orbit. These included a Returner Mars sample collector, a Mars Lander (based on JPL's lunar Surveyor), impact probes (based on JPL's lunar Ranger) to investigate Phobos and Deimos, and a Mars Environmental Satellite orbiter. It was even suggested that the Returner could be modified to a two man Mars Excursion Vehicle, which would deliver two men to the Martian surface for a seven-day visit to the surface.


Crew Size: 8.

AKA: Early Manned Planetary - Interplanetary Roundtrip Expedition.
Gross mass: 900,000 kg (1,980,000 lb).
Height: 95.00 m (311.00 ft).
Diameter: 23.00 m (75.00 ft).
Thrust: 1.78 kN (401 lbf).
Specific impulse: 800 s.

More... - Chronology...

Associated Countries
Associated Engines
  • Nerva DoE nuclear/lh2 rocket engine. 266 kN. Study 1968. Early version of Nerva engine proposed for use in Saturn and RIFT configurations in 1961. Isp=800s. More...

See also
  • Mars Expeditions Since Wernher von Braun first sketched out his Marsprojekt in 1946, a succession of designs and mission profiles were seriously studied in the United States and the Soviet Union. By the late 1960's Von Braun had come to favour nuclear thermal rocket powered expeditions, while his Soviet counterpart Korolev decided that nuclear electric propulsion was the way to go. All such work stopped in both countries in the 1970's, after the cancellation of the Apollo program in the United States and the N1 booster in the Soviet Union. More...

Associated Manufacturers and Agencies
  • Convair American manufacturer of rockets, spacecraft, and rocket engines. Convair, USA. More...

Associated Propellants
  • Nuclear/LH2 Nuclear thermal engines use the heat of a nuclear reactor to heat a propellant. Although early Russian designs used ammonia or alcohol as propellant, the ideal working fluid for space applications is the liquid form of the lightest element, hydrogen. Nuclear engines would have twice the performance of conventional chemical rocket engines. Although successfully ground-tested in both Russia and America, they have never been flown due primarily to environmental and safety concerns. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

  • Miller, Ron, The Dream Machines, Krieger, Malabar, Florida, 1993.
  • Portree, David S. F., Humans to Mars: Fifty Years of Mission Planning, 1950 - 2000, NASA Monographs in Aerospace History Series, Number 21, February 2001.

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